A sportsman facing sex charges wants a judge at his looming trial to step aside after she aired concerns with John Campbell about low conviction rates in similar cases.

The sportsman's lawyer also suggested Judge Kirsten Lummis, previously a Crown prosecutor with Meredith Connell, was too close to the prosecution in the case.

But a High Court judge today said "judge-shopping" was unacceptable and in New Zealand, prosecutors were often promoted to become judges.

"That fact can't be enough to disqualify judges," he told the defence lawyer.

For reasons not immediately clear, the sportsman's name was on a public document, despite him having name suppression.

As a result, naming the lawyers or judge at today's hearing could also lead to the sportsman's identification.

His trial on charges including indecent assaults and strangulation is due to start this month at the Sexual Violence Pilot Court.

His defence counsel raised three issues at today's hearing.

The lawyer said when Judge Lummis was a prosecutor in 2019, she outlined concerns to Campbell on TV One's Breakfast show.

The programme said 76 per cent of all prosecutions for adults the previous year resulted in convictions, but only 51 per cent of sexual assault and related cases led to convictions.

"We're still coming up against victim-blaming," Lummis told Campbell in the interview.

The athlete's defence said this raised potential apprehended bias and fair trial rights issues.

"In any sexual violence case, the judge does have a more sensitive and attuned role in shaping the evidence that goes to the jury," the defence lawyer said.

The lawyer claimed that cross-examination questions often had to go to the judge before the questions were delivered in court.

But the High Court judge today said he didn't accept judges played a greater role in sexual violence cases than in other cases.

"It's not my experience ... that cross-examining questions are put to the judge beforehand," he added.

The athlete's defence said it was concerned that Judge Lummis, before her promotion, signed a Crown Prosecution Notice for the sportsman's case.

The High Court judge today said the signature was a simple administrative occurrence.

The defence disagreed.

"You're entitled in New Zealand to have a completely separate judge and prosecutor in my opinion," the defence counsel said.

"It's just the appearance of bias ... Saying it's purely administrative is a really difficult concept for the layperson."

According to the Ministry of Justice, when the Crown assumes responsibility for a prosecution, it must file a notice to that effect.

In a third point, the defence argued Judge Lummis was too close to the prosecutor.

The defence said Judge Lummis once asked the prosecutor "on the spot" to remind her if she'd previously had a substantial involvement in the athlete's file.

"It's such an awkward situation," the defence counsel said.

But the High Court judge disagreed.

"It's not awkward at all. It just has to be raised in the open and here it was raised in the open."

And he said 11th-hour applications for recusal could be hugely disruptive.

The prosecutor said Judge Lummis had only been one of several supervisors he'd had at Meredith Connell.

"She wasn't my sole supervisor."

The High Court judge reserved his decision, meaning he will issue his judgment later.

Judge Lummis previously refused a defence application for her recusal, and had already disclosed she'd signed the Crown Prosecution Notice.

Judge Lummis also disclosed previously that she'd been the prosecutor's supervising partner.

This afternoon, the Office of the Chief Justice was approached for comment on the case.

A spokeswoman from the office said: "Judges would never comment on a court proceeding."